Many viscous salad dressings are oil-in-water emulsions and have certain product properties, such as viscosity, physical stability, and rheological behavior. An emulsion is a preparation established with the use of an emulsifying agent of a deformable liquid (the internal or discontinuous phase) distributed in small globules throughout the body of a second liquid (the external or continuous phase). The continuous phase of the emulsion forms a layer adsorbed around the globules of the discontinuous phase. This modifies the forces of cohesion between these globules, and the forces between these globules in the continuous phase. The globules of the discontinuous phase are generally held together by London-Van der Waals attraction forces, and often form aggregates. Usually, the emulsifier is dissolved, or dispersed, in the continuous phases. An oil-in-water emulsion has oil as the discontinuous phase and an aqueous solution as the continuous phase.
It is generally beneficial to increase the viscosity and/or yield stress of viscous oil-in-water food products (i.e., salad dressings) because such an increase in the rheological properties permits the food products to achieve a desired level of yield stress (i.e., a desired degree of gelation of a spoonable salad dressing or mayonnaise) with the use of smaller quantities of oil. The reduced oil levels can result in a cost savings for preparing the food products. In addition, reduced-fat properties of such food products are a benefit to overweight and obese consumers and/or consumers wishing to reduce fats in their diets. Additionally, a relatively constant yield stress for such oil-in-water emulsion food products (e.g., salad dressings) over time is generally positively correlated with the physical stability of the food products. Thus, oil-in-water emulsion viscous dressing products having a higher yield stress maintained over time will generally also be more stable. It is beneficial to control the stability and rheology of such food products because such control permits the preparation of viscous salad dressings and/or mayonnaise having enhanced flavor and texture qualities.
In addition, conductivity and particle size detection can also be used to measure the stability of oil-in-water emulsions. The stability of an oil-in-water emulsion can be assessed by subjecting the emulsion to centrifugation. For an unstable emulsion, centrifugation at 4000.times.G for 30 minutes generally results in two new layers: a top cream phase layer and a lower aqueous layer. It may be determined whether an oil layer has formed upon centrifugation of an oil-in-water emulsion by taking a sample of the top layer of the emulsion before centrifugation and a sample of the top layer of the emulsion after centrifugation, dropping each into separate water samples, and testing the conductivity of those water samples. Lower conductivity in the water to which the top layer of the sample subjected to centrifugation has been added indicates that fewer ions are available to detection by conductivity, and this is an indication of the appearance of a cream phase from the emulsion upon centrifugation. Thus, if conductivity drops significantly upon centrifugation, then the emulsion has broken and the emulsion is generally considered as not stable.
Stability of an oil-in-water emulsion can also be tested using particle size measurements. The particle size of oil droplets within the aqueous phase can be determined. Droplets of a narrow range of relatively small sizes are generally indicative of relatively stable emulsions. Such emulsions generally will maintain their emulsified state upon harsh treatment (i.e., centrifugation at 4,000.times.G for 30 minutes or storage at room temperature for extended periods of time (i.e., months)).
Conventionally, viscous salad dressings use carbohydrates such as starches, and/or cellulose gels and/or gums to provide body (i.e., increase the yield stress of the final product) and stability. Conventionally, viscous salad dressings are manufactured using a two stage process as illustrated in FIG. 1. First, a premix is prepared containing water, oil, eggs or egg products, salt, sugar, and spices. The premix is subjected to high shear to form an emulsion. Second, a starch base is prepared by cooking an aqueous starch mixture; the mixture can contain optional ingredients such as sugar, vinegar, spices, and the like. After cooling, the starch base is added to the premix emulsion as a separate stream under low pressure conditions. The resulting emulsion or dispersion is subjected to low shear to form the desired viscous dressings.
Addition of conventional starches (i.e., without cooking) with the rest of the ingredients and then subjecting such a mixture to high shear produces salad dressings which are usually thin and unstable (i.e., the emulsion breaks, releasing a free oil phase and a free aqueous phase). Thus, this conventional process requires the formation of two different mixtures, and the addition of the starch base to the premix emulsion only after the high shear treatment is completed, to form the emulsion.
Using the formulations and methods of the present invention, viscous dressings can be prepared using a so-called one-pot or single pot preparation. The viscous dressing products generated using the process of this invention display similar rheological properties, particle size, and conductivity properties as viscous salad dressings which have been prepared using conventional and more complex processes (i.e., FIG. 1). In the present invention, it is not necessary to cook the starch base, cool it, and then add it to the premix to generate the viscous dressing product.
Because the present invention allows preparation of viscous dressing products in a single pot or vessel, the separate starch preparation steps of the conventional process are eliminated. Thus, the present invention provides a simpler, more cost effective method of preparing salad dressing and mayonnaise products while maintaining desired organoleptic properties.
Mayonnaise has a Food and Drug Administration ("FDA") Standard of Identity as being composed of 65% fat, and in which carbohydrates may be added merely as sweeteners. However, starch or carbohydrate may be added to reduced-fat, low-fat, light and fat-free mayonnaise as bulking agents. Salad dressing has an FDA Standard of Identity as an emulsified semisolid food prepared from vegetable oils, one or more of acidifying ingredients, one or more of egg yolk-containing ingredients, and a starchy paste. The FDA nutritional labeling regulations recognize "reduced-fat" foods as foods that have at least 25% less fat than an appropriate reference food. "Low-fat" products contain .ltoreq.3 g of fat per reference amount and per 50 g if the reference amount is 30 g or less. A product may be identified as "light" based on either a .gtoreq.331/3% reduction in calories or a .gtoreq.50% reduction in fat when compared to an appropriate reference food. However, if the "light" product derives .gtoreq.50% of its calories from fat, then the product must be reduced in fat by at least 50% compared to the reference food. "Fat-free" products have less than 1/2 gram fat per reference amount.
For purposes of this disclosure, the term "reduced-fat" viscous salad dressing is intended to include "reduced-fat" viscous salad dressings, "low-fat" viscous salad dressings, and "light" viscous salad dressings as defined by the FDA nutritional labeling regulations. In addition, for purposes of this disclosure, the term "light" viscous salad dressing is intended to include "light" viscous salad dressings as defined by the FDA nutritional labeling regulations ; the term "fat-free" viscous salad dressings is intended to include "fat-free" viscous salad dressings as defined by the FDA nutritional labeling regulations .
In addition, because, by definition, a full-fat mayonnaise cannot contain starches, gums and/or other carbohydrates (except as sweeteners), this disclosure refers to reduced-fat, low-fat, light, and fat-free mayonnaise as "reduced-fat" mayonnaise throughout much of the disclosure. However, for specific embodiments for preparing light mayonnaise alone, the term "light mayonnaise" is used. Likewise, for specific embodiments for preparing fat-free mayonnaise, the term "fat-free mayonnaise" is used.
In addition, viscous dressing products that do not fall into the categories defined by the FDA nutritional labeling regulations (at the time of this disclosure) are encompassed within the bounds of this invention. Such compositions and the methods for making them may be described by the amount of fat contained therein or by the reduction of fat content as compared to the full-fat counterpart.
It is an object of the present disclosure to provide viscous dressing products, such as, for example, viscous salad dressing and reduced-fat mayonnaise, which may be prepared in a streamlined manner using a one-pot system and high shear to provide viscous dressing products having desirable rheological, mouthfeel, and taste characteristics.
It is a further object of the present disclosure to provide methods for preparing viscous dressing products using a streamlined process employing a one-pot system and high shear to yield viscous dressing products with desirable rheological, mouthfeel, and taste characteristics.